1. Field of the Invention
The present invention relates to a method of manufacturing a hose, having an expanded portion and a compression formed portion, that is particularly suitable for use as an automobile fuel inlet hose.
2. Description of Related Art
Conventional automobile inlet fuel hoses can be formed with an expanded portion such as a bellows tubular portion which allows them to bend easily during installation. In other words, the elongation and the flexibility of the bellows tubular portion are utilized when installing the hose. Also, assembly errors can be absorbed or accommodated by the bellows tubular portion. During operation of the automobile, vibrations can be also absorbed by the bellows tubular portion.
Hoses are generally formed by extrusion. However, it is impractical to make hoses having an expanded bellows portion by extrusion. Therefore, hoses having expanded portions are generally molded, for example, by using injection or blow molding equipment. Such a hose is disclosed, for example, in Japanese Utility Model Laid-open publication No. Hei 03-119691.
Fuel inlet hoses are generally made of two kinds of different materials and can be comprised of a two layered structure or a double tube construction. However, it is not desirable to form a fuel inlet hose having the expanded portion and the two layered structure by using injection molding techniques. That increases the complexity of the manufacturing process, the steps involved and the cost.
Another method for producing a bellows tubular shape uses pressurized fluid. For example, pressurized air is forced into a parison or an extruded tube, and it expands the tube into the mold cavity forcing the tube to conform to the mold cavity surface. Such a method is disclosed, for example, in Japanese Patent Laid-open publication No. Hei 05-57812.
Fuel inlet hoses must be connected to other types of hoses as well as to other members, for example, a pipe, a fuel tank. In such a case, it is desirable to form the tube with structure that will aid or assist its connection to other members. One such structure which will aid in determining when a proper connection is formed, includes setting and positioning parts. Such parts can be formed on the inner surface or on the outer surface of one end portion of the hose, for aiding the setting and positioning of the hose with the other member. Such a hose, having setting and positioning parts, is disclosed, for example, in Japanese Utility Model Laid-open publication No. Hei 03-119691.
It is also desirable to form a tapered guide surface at an open end portion of the inner surface of the hose for guiding the other member when the hose is connected to the other member.
The blow molding manufacturing method, disclosed in Japanese Patent Laid-open publication No. Hei 05-57812, is impractical for forming the inner surface of the hose since it only helps form the outer surface where the hose is expanded. Blow molding is also impractical for making setting and positioning parts.